package com.hmdp.utils;

import cn.hutool.core.lang.UUID;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.data.redis.core.script.RedisScript;

import java.util.Collections;
import java.util.concurrent.TimeUnit;
//用redisson里的方法完成了该功能,获取锁和释放锁
public class SimpleRedisLock implements ILock{

    private String name;
    private StringRedisTemplate stringRedisTemplate;
    private static final String KEY_PREFIX = "lock:";
    //toString(true)可以去除UUID的横线，并拼接"-"区分UUID
    private static final String ID_PREFIX = UUID.randomUUID().toString(true) + "-";

    //ctrl+shift+u
    private static final DefaultRedisScript<Long> UNLOCK_SCRIPT;
    static {
        UNLOCK_SCRIPT =new DefaultRedisScript<>();
        UNLOCK_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
        UNLOCK_SCRIPT.setResultType(long.class);
    }

    public SimpleRedisLock(String name, StringRedisTemplate stringRedisTemplate) {
        this.name = name;
        this.stringRedisTemplate = stringRedisTemplate;
    }

    @Override
    public boolean tryLock(long timeoutSec) {
        //使用UUID获取线程唯一标识，虽然线程的id是自增的，但在集群模式下线程的id可能会重复
        String threadId = ID_PREFIX + Thread.currentThread().getId();
        //获取锁
        Boolean success = stringRedisTemplate.opsForValue()
                .setIfAbsent(KEY_PREFIX + name, threadId , timeoutSec, TimeUnit.SECONDS);

        //不能直接return success 因为Boolean -> boolean 自动插箱可能会返回空值
        return Boolean.TRUE.equals(success);
    }

    @Override
    public void unlock() {
        //调用lua脚本
        stringRedisTemplate.execute(
                UNLOCK_SCRIPT,
                //单元素的集合，把一个元素变成一个只有一个元素的集合
                Collections.singletonList(KEY_PREFIX + name),
                ID_PREFIX + Thread.currentThread().getId());
    }

//    @Override
//    public void unlock() {
//        //获取线程标识
//        String threadId = ID_PREFIX + Thread.currentThread().getId();
//        //获取锁中标识
//        String id = stringRedisTemplate.opsForValue().get(KEY_PREFIX + name);
//        //判断标识是否一致
//        if(threadId.equals(id)) {
//            //释放锁
//            stringRedisTemplate.delete(KEY_PREFIX + name);
//        }
//    }
}
